You act like SCOTUS would need to defend it. Assuming Thomas and Alito step down in the next 4 years, Trump has two open slots to fill with other younger bucks like he did in 2016, and without a Dem lockup in Congress to actually impeach anyone over their decisions, the decisions they make could theoretically stand unchallenged for decades.
Nah, Reagan did it easy. Plenty of people will be totally ok with banning guns if THOSE PEOPLE start carrying and using them.